import React, { Component } from "react";
import ReactDOM from "react-dom/client";

const root = ReactDOM.createRoot(document.getElementById('root'))

function Header () {
  return (
    <header> 头部 </header>
  )
}

const Content = () => {
  return (
    <main> 内容部分 <MyBtn></MyBtn> </main>
  )
}
function MyBtn () {
  return (
    <button>求点击</button>
  )
}

class App extends Component {
  render () {
    return (<>
      <h1>react {1 + 3}</h1>
      <Header ></Header>
      <Content />
    </>)
  }
}


root.render(
  <App />
)
